Tips For Working Out in the 3rd Trimester

Hello everyone! I am currently 27 weeks pregnant! My due date is September 17th. This is my first pregnancy. I haven't consistently worked out in a long time since highschool (I am now 22). I really regret not keeping up with it and would like to start now. I'm not really worried about losing weight after giving birth. I'm more worried about being healthy and preparing my body to give birth. I'm not really sure how to approach it safely. I'm also anxious about accidentally causing early labor. I'm not in budget to hire a trainer for help at this time. Any tips or advice to help me get started? Most appreciated!!